•The US is increasing its efforts to persuade Yemen's veteran president to step down before escalating fighting between the government and tribal rebels develops into civil war, Ian Black writes. Reports from Sana'a said Saleh's forces were deploying heavy weapons at the entrance to the city to prevent the advance of rebels loyal to Sheikh Sadiq al-Ahmar, chief of the Hashid tribal federation, the country's largest. At least 135 people have been killed in the last 10 days.

•About 250 people are feared to have drowned after their attempt to flee the violence in Libya apparently ended in tragedy off the Tunisian coast, says John Hooper. Coastguards and military personnel are reported to have saved at least 570 people, all from sub-Saharan Africa, during a rescue operation in rough seas and shallow waters off the Kerkennah islands east of the Tunisian coast.

•Formula 1's governing body will meet today to decide the fate of the Bahrain grand prix. Bahrain had been due to host the opening race of the 2011 season but it was called off amid unrest in the country. Organisers have asked for the race to be rescheduled, although some have called for it to be cancelled.

Follow live updates from across the region here.

10.31am: Reuters reports that forces loyal to Yemeni President Ali Abdullah Saleh have fired at protesters in Sana'a this morning.

In other parts of the capital, tribesmen siding with the protesters have fought pitched street battles with Saleh's troops, including his special forces which were set up to fight al Qaeda, for control of government buildings.

More than 350 people have been killed since the uprising started in January, but least 135 of them have been killed in the past 10 days in a marked escalation that began when tribal groups started fighting government troops in the capital Sana'a.

Worries are growing that Yemen, home to a branch of al-Qaeda known as AQAP and next to the world's biggest oil exporter Saudi Arabia, could implode and become a failed state that poses a risk to global oil supplies and security.

Political veteran Saleh has backed away three times at the last minute from signing a Gulf-led deal to step down, clinging to power despite global pressure to resign and the defection of ministers and military leaders to the opposition.

"But even if the president would agree, and so far he has shown no intention, one could not ensure the transition to go smoothly given that there are so many risks involved," said Christian Koch, director of international studies at the Gulf Research Center in Dubai.

Saleh's special forces were deployed to help "clean up" a ministry held by tribal forces, the Defence Ministry said on Thursday, as battles near the airport briefly grounded flights.

10.41am: The Times has an interesting piece today from Iona Criag in Sana'a, about water running out in the Yemeni capital (paywall).

The price of water trebled overnight in Yemen's battle-scarred capital and basic provisions were dwindling as thousands of tribesmen fought their way into Sana'a yesterday to join the rebellion against President Saleh...

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Amid the ancient tower houses of Sana'a's Old City, men, women and children rushed to a water tanker when it arrived outside a mosque yesterday. Tensions rose as residents jostled to fill cans and plastic containers.

The cost of a water tanker delivery, usually 1,300 Yemeni rials (£3.50), soared to 7,000 amid the escalating conflict. With 40 per cent of Yemen's 23 million people living on less than £1.50 a day, the prices will inevitable add to the cycle of violence.

"They spend their money on bullets, but I can't even afford water for my family," shouted one desperate resident as he waited for his can to fill from a communal water tanker.

Yemen already has really bad problems with water, with the wells of Sana'a expected to run dry by 2015 – check out this audio slideshow, produced before the Middle East unrest, on the water crisis in the country.

11.12am: Protests are planned in Syria today to mark "children's Friday", in memory of Hamza al-Khatib, a 13-year-old boy who was killed in the Deraa area and whose battered and mutilated corpse has become a rallying-point for anger at the regime of President Bashar al-Assad, Ian Black wrote yesterday.

Ammar Qurabi, head of the Syrian Organisation for Human Rights, referred to the names of 1,113 civilians killed since the protests erupted on 18 March. International media are banned by a government which talks of facing "armed terrorist gangs" not largely peaceful protests.

Although media are banned, it is possible to get some reports from the country. The Guardian has been told that the internet is not working "anywhere in the country" today – previously the al-Assad regime has attempted to block web access.

11.26am: The bodies of 150 African refugees have been recovered off the Tunisian coast after the vessels carrying them illegally to Europe got into difficulty earlier in the week, according to a UN official earlier we heard 250 people were believed to be missing.

The downtown square was the epicenter of weeks of Shiite-led protests against Sunni rulers earlier this year in the Gulf kingdom.

Friday's march in Manama comes two days after authorities lifted emergency rule. It was imposed in March to quell demonstrations by Bahrain's Shiite majority demanding greater freedoms and inspired by uprisings across the Arab world.

At least 30 people have died since February, when protests erupted in the tiny island nation, which hosts the US Navy's 5th Fleet.

There were no immediate reports of injuries. The eyewitnesses spoke on condition of anonymity, fearing reprisals.

In the run up to the decision on Formula One, police patrols have sought to prevent any demonstrations and controversial trials of pro-democracy protesters have been postponed. Ayat al-Gormezi, the 20-year-old girl poet, who was to be tried by a military tribunal on a charge of stirring up hatred and insulting the King, has had her trial put off until 6 June.

Of the 108 local staff of the government-owned Bahrain International Circuit (BIC), which hosts Formula One, some 28 were detained and mistreated according to a source in Bahrain close to the event. All of those arrested are Shia and have since been sacked. Five of these are still in prison including the chief financial officer Jaafar Almansoor, an employee of BIC told Reuters news agency.

"They made us beat and kick each other," said the employee, who did not want to be named, describing their 20 days in detention. "They said they'd rape us. They tried to touch you in various places to make you think it's going to happen." The prisoners were insulted for being Shia and, on being released, were told not to talk to the media.

This morning Bernie Ecclestone, the Formula One commercial rights holder, said that a decision on whether to reschedule the postponed grand prix will have "nothing to do with money".

12.32pm: A Bahraini government official has said that the Bahrain grand prix will go ahead. More as we get it.

12.42pm: Fawaz al-Khalifa is the Bahraini government official who appears to have broken the news – via Twitter.

Al-Khalifa has since tweeted saying that FIA are now "finalising [the] date".

1.05pm: Yemen's deputy prime minister has been injured after the presidential palace was hit by two shells amid street fighting in Sana'a, according to al-Arabiya TV.

Battles in Sana'a have widened today, Reuters reported earlier. It said 155 people have been killed over the last 10 days, marking an escalation in the uprising to end President Saleh's three-decade long rule. About 370 people have been killed in total.

1.11pm: No confirmation from the FIA – formula one's governing body – about the Bahrain grand prix yet. I have just called the organisation's head office in France, but unfortunately the only press officer able to speak on this issue is out for the next hour.

1.31pm: A significant Yemen update:

President Saleh has been injured in a shell attack, Reuters reports. It says:

Yemen's President Ali Abdullah Saleh was injured, four of his guards killed and the speaker of parliament left in critical condition after the presidential palace was hit by shells on Friday, Al Arabiya TV reported.The prime minister was also injured in the attacks as street fighting between Saleh's forces and a tribal federation widened on Friday in the capital.

1.37pm:Yemen's President Saleh has been killed in the shelling, a local TV station loyal to the country's opposition has said.

There is no immediate way to verify this.

1.39pm: There's great confusion over this. Al Arabiya appears to also be reporting that Saleh is dead, but some tweets say he survived the attack and plans to hold a press conference.

1.41pm: Some Reuters news flashes are reiterating this latter news – President Saleh is not only alive but planning to hold an imminent news conference. This all comes from ruling party officials and cannot, as ever, be immediately verified.

1.44pm: AP have an update, via Yemen government officials:

Official: Yemen president lightly wounded when rockets hit in palace in Sanaa fighting.

1.46pm: That apparent press conference by President Saleh will take place in one hour, officials tell Reuters.

The weight of reports do seem to indicate that Saleh is not dead, and while he was hurt during a shell or rocket attack on the presidential palace he remains able to carry on. Once again: there is, as yet, no way of knowing for certain given the chaotic, ever-changing situation in Sana'a.

1.51pm: Here's a fuller AP take on the news:

A government official says Yemen's president was lightly injured and four top officials wounded when opposition tribesmen struck his palace with rockets.It was the first time that tribesmen have targeted President Ali Abdullah Saleh's palace in nearly two weeks of heavy fighting with government troops in the capital.The official says the rockets hit while officials were praying at a mosque inside the palace compound.He says Saleh, the prime minister, the deputy prime minister, the parliament chief and a presidential aide were wounded Saleh lightly, while the deputy prime minister and aide's wounds were serious. The official spoke on condition of anonymity because of the sensitivity of the situation.

1.55pm: Back briefly to the Bahrain grand prix – see also our separate story – the Bahrain race organisers have, not unexpectedly, welcomed the decision to hold the race.

The chairman of the Bahrain International Circuit company, Zayed Alzayani, said:

This is welcome news for all of Bahrain. As a country we have faced a difficult time, but stability has returned; with businesses operating close to normal, the State of National Safety lifted and countries removing travel restrictions.

Collectively, we are in the process of addressing issues of national and international concern, and learning lessons from the recent past. By the time the Grand Prix arrives we will be able to remind the world about Bahrain at its best.

The Bahrain Grand Prix has always been a source of national pride and it is an event than transcends politics. Not only does it receive strong support from the government, but also from all major parties in Bahrain, including our largest opposition group, Al Wefaq, who yesterday endorsed both the BIC and motor-racing in Bahrain.

Importantly, it will also offer a significant boost to the economy. The Grand Prix attracts 100,000 visitors, supports 3,000 jobs and generates around $500m of economic benefit. Its positive effect will be felt throughout the country.

On behalf of Bahrain, I would like to thank Bernie Ecclestone, Jean Todt and the FIA and the rest of the motorsport community for the support and understanding they have extended to us this year.

2.12pm: I've just been speaking, over a slightly crackly phone line, to Shadha Al-Harazi, a journalist at the Yemen Times in Sana'a, where the situation is increasingly chaotic. She has also been told via her own sources that President Saleh was injured.

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2.31pm: Saleh's news conference is expected to take place in around an hour, according to al-Jazeera.

2.34pm: But wait, Yemeni TV apparently is saying there will not be a press conference. Instead a statement will be issued. Confusing reports at the moment.

2.46pm: At least 10 people have been killed by Syrian security forces, according to the Syrian rights group Sawasieh.

Reuters reported they were shot dead as protesters defied a widespread military crackdown to demand President Bashar al-Assad leave office.

Three residents said security forces and snipers fired at tens of thousands of demonstrators gathered in the city centre in one of the biggest protests seen so far in Hama, and scores of wounded were taken to a nearby hospital.

Rami Abdulrahman of the Syrian Observatory for Human Rights put the death toll in Hama at 8.

Protests in Hama have a particular resonance, since the city was attacked in 1982 by Assad's father, then President Hafez al-Assad, who crushed an armed Islamist uprising, killing up to 30,000 people and razing parts of the city to the ground.

3.10pm: The general consensus now is that Saleh will be issuing a statement, instead of giving a press conference. We'll have news of that as we get it.

In the meantime, Reuters is reporting that Saleh's forces have "shelled the homes of the leaders of a powerful tribal federation at the forefront of deadly street fighting in the capital", according to security sources.

In a separate report, al-Arabiya TV has said the government blamed the tribal group led by Sadeq al-Ahmar for the presidential palace attack that reportedly injured the president and other government officials.

3.21pm: The Syrian observatory for Human Rights has said that Syrian security forces have now killed 27 protesters in the city of Hama.

"There are also scores of wounded and the death toll may rise," the Observatory's Rami Abdulrahman told Reuters.

Tens of thousands have been demonstrating against President Bashar al-Assad's rule.

3.49pm: I've just spoken to Ibrahim Mothana, 22, who lives about 2km away from the presidential palace which was hit by shells earlier today.

"Just after the Friday prayer, at around 12.45pm, then bombardment started towards Sheik Hamid al-Ahmar's house. I then started hearing of clashes around the presidential palace," he said.

Mothana, a 22-year-old student at the university of science and technology, said he had friends in the square near the palace: "People there were happy to hear that he [the president] had been killed, but then the government denied that."

He added: "I felt a bit worried, because I thought this would mean more escalation. It was a bit scary, just hearing the consequences of what had happened, with injured, that for me means we will experience an escalation and it will probably be more violent."

Mothana said he was worried about what the attacks on the presidential palace could escalate fighting: "For the past 90 minutes things were calm, then we've heard again two huge explosions. I don't where they're coming from. I think there will be more clashes in the coming hours."

Graphic

This is Richard Adams in the Guardian's Washington bureau taking over live blogging duties.

4.17pm: The Associated Press's latest dispatch from Sana'a has an updated casualty count, saying that six guards at the presidential palace were killed and seven top officials injured, quoting an "official" who was at the scene:

A volley of three rockets hit Saleh's presidential compound Friday as he and other officials were praying at a mosque inside, the official said, speaking on condition of anonymity because of the sensitivity of the situation. Six presidential guards were killed, according to a medical official.

Seven top officials were wounded, including the prime minister, the deputy prime minister, the parliament speaker and the governor of Sana'a, the official said. The most serious injuries were to Sana'a's governor Nooman Dweid, and Deputy Prime Minister Rashad al-Alimi, who is also the president's top security adviser and who remained unconscious from his wounds, the official said.

5pm: Apologies for the delay in posting updates, we've had a software malfunction that has now been fixed.

5.21pm: Here's the latest Guardian video of the aftermath of Friday prayers in Sana'a.

5.39pm: The Guardian's Brian Whitaker ponders what the rocket attack on Saleh's presidential palace means for the unrest in the country, and considers the different scenarios:

In what might be the best scenario for Yemen's future, Saleh would be seriously injured but not dead. In fact, sufficiently injured for the doctors to decide that he needs urgent treatment abroad.

Flying him out of the country for medical reasons would provide a near-perfect exit from the crisis. The vice-president could take over and Yemen could begin to calm down. It's unlikely that anyone would want Saleh back if or when he recovered.

Probably the worst scenario would be a lightly-wounded president who returns to the fray within a day or two, with renewed ferocity, to wreak his revenge.

The least predictable scenario would be if Saleh has actually been killed. In theory, his vice-president should step into the breach while new elections are arranged, but there would also be a possibility of a power struggle behind the scenes if his death were concealed for long.

6.03pm: Al-Jazeera English is reporting rumours that Yemen's President Saleh has sustained more considerable injuries than is being officially acknowleged, with speculation that Saleh was wounded in his neck.

The official line is that he is in "good health" and will recover quickly. But there are still no signs of Saleh on television or in public, despite the several hours that have no passed.

The accuracy and sophistication of the rocket attack also suggests that a rebel military unit was more likely to have been the source of the attack.

6.26pm: Abdul Mohd il-Jindi, Yemen's deputy information minister, says President Saleh's planned public appearance today was postponed "because of scratches on his face" from the rocket attack on the presidential alace.

"His Excellency, the president is in good health and has postponed [his] press conference ... due to scratches. he will recover, god willing," Il-Jindi said. "There is nothing that affects his health."

6.45pm: Here's a round-up of the events today throughout the Middle East and North Africa:

•Yemen's President Ali Abdullah Saleh was wounded when his palace was hit by a rocket attack. At least six guards are killed and nine others were wounded, according to unconfirmed reports

•Saleh has not been seen in public since the attack. Saleh suffered slight injuries to his neck and face, and taken to a hospital for treatment but is "in good health" according to official statements

•In Syria, the military violently attacked anti-government protests, with 34 people said to be killed in Hama where eyewitnesses said around 150,000 demonstrators on the streets of the city

•Syrian authorities cut internet connections across the country, in an attempt to cut off outlets for rebel use of YouTube and Facebook services, along with email

•Bahrain's police fired tear gas at protesters marching toward the landmark Pearl Square in the country's capital, the first major protest for two months.

•Formula 1's governing body ruled that the Bahrain Grand Prix in October could go ahead, despite the continuing unrest in the tiny state

•Rebel fighters in Libya says its supporters have taken control of towns in the western Nafusa mountain range, where pro-Gaddafi forces had attacked rebels areas for seveal months

•UN officials will meet with Iman el-Obeidi, who says she was raped by Gadhafi's troops. The Libyan woman was deported from Qatar yesterday and was flown against her will to Benghazi

•In Jordan, around 3,000 protesters marched in several cities, calling on Prime Minister Marouf al-Bakhit to resign after failing to deliver political reforms and new elections

7.12pm: Not everyone is happy with the decision for the Bahrain grand prix to go ahead. Pitpass website points out a lukewarm statement from the Red Bull Formula 1 team:

7.28pm: Yemen's president Ali Abdullah Saleh is said to be about to appear on Yemen's state television, so stay tuned.

7.50pm: Yemen's president has been speaking on state television, but it appears to be audio only. Still trying to get details.

8.01pm: Yemen's state television has played what appears to be a minute-long audio tape of President Ali Abdullah Saleh, speaking about the attack that killed several of his guards and associates.

Saleh's injuries were said to be minor, and on the recording he said that seven people were killed, and labelled the attackers "a bunch of thugs" according to a brief translation offered by Al-Jazeera English.

In his statement Saleh said he was well but appeared to sound as if he was short of breath, according to those who heard it.

Al-Jazerra's correspondent says that Saleh's voice is tired compared to his usual tone, that he may have suffered a serious injury and wasn't speaking in clear sentences.

Update: here is a Youtube video of Saleh's audio address on Yemen state television.

It was a violent end to a violent week. On Thursday government jets strafed roads and villages north of Sana'a as thousands of tribesmen tried to enter the capital to fight Saleh loyalists. Residents described an atmosphere of fear and alarm at food shortages and rising prices.

Time to wrap up this live blog for the evening – and you can continue to follow the latest breaking news on the Guardian's world news page.